Sharpie is to sell a 'liquid pencil,' a pen with erasable ink made from graphite that only becomes permanent after three days' exposure to the air. In the meantime, it may be rubbed out with a standard eraser. It'll hit stores this fall. Introducing The NEW Sharpie LIQUID PENCIL [Sharpie via Wired] Update: WordPressfail. Updated link to point to google cache.